This invention relates to electrically conducting materials, and is particularly directed to dielectric substrates containing an inorganic conductive coating having high temperature stability, and to a process for the preparation of such articles.
Existing stable organic conducting polymer systems, e.g., polypyrrole, have been found highly useful for production of conductive structural composites, particularly in the aircraft industry. While the processing features of polypyrrole for large scale applications have been found excellent, such conductive polymers have exhibited electrical instability at temperatures greater than 400.degree. F. Advanced aircraft designs which may incorporate these materials can require such temperatures to cure resins, such as epoxies and bismaleimides, used for encapsulating or forming conductive composites with such conductive material, such as polypyrrole.
Electrically conducting copper sulfide coatings on substrates are known. Thus, European Patent No. 160,406, published Nov. 6, 1985, discloses electrically conductive cupric sulfide coated polymers, prepared by treating polymers, such as acrylic fabric, with an aqueous solution containing cupric sulfate and sodium thiosulfate to form an electrically conductive cuprous sulfide layer. The cloth is then sulfurized in a toluene solution of sulfur containing butylamine.
Japanese Application No. 83/240,918, published Dec. 22, 1983, discloses conductive fibers coated and/or filled with CuS. Thus, acrylonitrile-methylmethacrylate-sodium styrenesulfonate copolymer fibers were soaked in aqueous cupric sulfate-sodium thiosulfate solution and heated at 95.degree. C. to give fibers coated with CuS.
It is known that nickel sulfide can be precipitated by boiling a nickel salt solution with sodium thiosulfate.
An object of the present invention is the production of dielectric substrates, such as fiberglass cloth, containing an electrically conductive inorganic coating having electrical stability at high temperatures, and the provision of a process for producing such electrically conductive substrates.
Another object is the preparation of dielectric substrates, e.g., of structural fabrics, such as fiberglass cloth, containing an inorganic electrically conductive coating having good adhesion to the substrate, and having good electrically conductivity, and which can be applied to the substrate using large scale applications and simple processing techniques.